CVE-2021-39881Public exploitNetwork attack vector

Authorization deception via unchecked OAuth scope names

Published Oct 5, 2021 · Updated Aug 4, 2024

OAuth scope spoofing in affected GitLab releases allows remote authenticated users to trick users into authorizing malicious clients. Application creation and update accept scope values without checking that they are a subset of predefined scopes, then display attacker-supplied scope text on the OAuth consent screen. A GitLab account is required to register the application, and a victim must open its authorization request and approve access, yielding an OAuth token to the attacker-controlled client.

CVSS severity3.5
Low
EPSS probability0.88%
Next 30 days · Sep 16, 2026
Known exploitationUnconfirmed
Based on sourced intelligence
Hinoki checkNot available
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Summary

What happened

OAuth scope spoofing in affected GitLab releases allows remote authenticated users to trick users into authorizing malicious clients. Application creation and update accept scope values without checking that they are a subset of predefined scopes, then display attacker-supplied scope text on the OAuth consent screen. A GitLab account is required to register the application, and a victim must open its authorization request and approve access, yielding an OAuth token to the attacker-controlled client.

The record

CVE
CVE-2021-39881
Published
Oct 5, 2021
Updated
Aug 4, 2024
Vendor
GitLab
Product
GitLab
Classifications
T1528
Attack vector
network
Privileges
authenticated

Timeline

How it unfolded

  1. Oct 5, 2021CVE publishedPublication date reported by the CVE source.
  2. Aug 4, 2024Record updatedLatest update available in the CVE record.

Exploitability

Present is not the same as exploitable

Compare your product and version with the public record. A matching version still requires validation against your environment.

Is a vulnerable build present?

Compare these published version ranges with your installed build and any vendor patches.

  1. Affected versionversion=>=14.2, <14.2.5
  2. Affected versionversion=>=14.3, <14.3.1
  3. Affected versionversion=>=7.7, <14.1.7

What conditions does exploitation require?

Attack vectornetwork
Required privilegesauthenticated

What is affected?

GitLab · GitLabversion=>=14.2, <14.2.5; version=>=14.3, <14.3.1; version=>=7.7, <14.1.7

Published CVSS scores

3.5GitLab Inc.CVSS:3.1/AV:N/AC:L/PR:L/UI:R/S:U/C:N/I:L/A:N
3.5NIST NVDAV:N/AC:M/Au:S/C:N/I:P/A:N

CVSS describes severity. EPSS estimates exploitation probability.

Attacks

What attackers are doing with it

Daily unique IPs observed by Shadowserver honeypots for known exploited vulnerabilities (KEVs). Missing observations do not establish an absence of attacks.

Daily unique IPsNo honeypot observations are available for this CVE in the selected window.

No observations available

Sep 10, 2026Sep 16, 2026
Latest reporting daySep 16, 2026
Latest daily unique IPsUnavailable
Prior 30-day averageUnavailable
SourceShadowserver honeypots (KEV)
Vectornetwork
Privilegesauthenticated
Known exploitationUnconfirmed
Public exploitPublished

Weakness, pattern, technique

T1528Steal Application Access Token

Public exploit references

Labels summarize the accepted research assessment. They do not indicate a test against your environment.

Technologies

Your stack

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Your stack

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